1. Field of the Invention
The present invention relates to a laminated balanced filter including a laminated body including a plurality of dielectric layers and a plurality of electrode patterns located on the dielectric layers and having a balanced-unbalanced transforming function.
2. Description of the Related Art
A known laminated balanced filter including a laminated body including a plurality of dielectric layers and a plurality of electrode patterns located on the dielectric layers and having a balanced-unbalanced transforming function is described in Japanese Unexamined Patent Application Publication No. 2011-124880. FIG. 8 is the exploded perspective view of the laminated balanced filter described in Japanese Unexamined Patent Application Publication No. 2011-124880, and FIG. 9 is the equivalent circuit diagram of this laminated balanced filter.
As illustrated in FIG. 8, this laminated balanced filter is configured using a laminated body where dielectric layers 251, 242, 241, 271, 211, 201, and 221 and electrode patterns 143, 142, 141, 131, 121, 120, 123, and 122 are laminated, the electrode patterns being formed on the dielectric layers. In addition, as illustrated in FIG. 9, this laminated balanced filter includes an unbalanced terminal T1 and balanced terminals T2 and T3. In addition, an LC parallel resonator is configured using an inductor L1 and a capacitor C1, configured by the electrode pattern 131, and one end portion of the corresponding LC parallel resonator is connected to the unbalanced terminal T1. Both end portions of an inductor L4 are individually connected to the balanced terminals T2 and T3.
In this circuit, the inductor L1 and the inductor L4 are coupled to each other, and accordingly, the corresponding laminated balanced filter turns out to have a balanced-unbalanced transforming function. In addition, inductors L2 and L3 and capacitors C2 and C3 function as a circuit for impedance matching and impedance conversion.